The left front and both rear speakers quit suddenly. The weird thing is that it happened and when I started the car next day they were back. Now all but the right front don't work. Any ideas? It'* a 02 Envoy, no XM radio. I can't even find any screws to get into the thing.

dont know how to take the envoy apart but generally there is a trim plate that has to be removed and they are usually held by clips that you have to pry out. as far as the problem you should take a known good speaker and put in the spot that doesnt work, then you know if it works the speaker is bad if not wither the radio is or the wires